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1 ConcepTest 11.1a Harmonic Motion I1) 02) A/23) A4) 2A5) 4AA mass on a spring in SHM has amplitude A and period T. What is the total distance traveled by the mass after a time interval T?

2 ConcepTest 11.1a Harmonic Motion I1) 02) A/23) A4) 2A5) 4AA mass on a spring in SHM has amplitude A and period T. What is the total distance traveled by the mass after a time interval T?In the time interval T (the period), the mass goes through one complete oscillation back to the starting point. The distance it covers is: A + A + A + A (4A).

3 ConcepTest 11.3a Spring Combination IA spring can be stretched a distance of 60 cm with an applied force of 1 N. If an identical spring is connected in parallel with the first spring, and both are pulled together, how much force will be required to stretch this parallel combination a distance of 60 cm?1) 1/4 N2) 1/2 N3) 1 N4) 2 N5) 4 N

4 ConcepTest 11.3a Spring Combination IA spring can be stretched a distance of 60 cm with an applied force of 1 N. If an identical spring is connected in parallel with the first spring, and both are pulled together, how much force will be required to stretch this parallel combination a distance of 60 cm?1) 1/4 N2) 1/2 N3) 1 N4) 2 N5) 4 NEach spring is still stretched 60 cm, so each spring requires 1 N of force. But since there are two springs, there must be a total of 2 N of force! Thus, the combination of two parallel springs behaves like a stronger spring!!

5 ConcepTest 11.4 To the Center of the EarthA hole is drilled through the center of Earth and emerges on the other side. You jump into the hole. What happens to you?1) you fall to the center and stop2) you go all the way through and continue off into space3) you fall to the other side of Earth and then return4) you won’t fall at all

6 ConcepTest 11.4 To the Center of the EarthA hole is drilled through the center of Earth and emerges on the other side. You jump into the hole. What happens to you?1) you fall to the center and stop2) you go all the way through and continue off into space3) you fall to the other side of Earth and then return4) you won’t fall at allYou fall through the hole. When you reach the center, you keep going because of your inertia. When you reach the other side, gravity pulls you back toward the center. This is Simple Harmonic Motion!Follow-up: Where is your acceleration zero?

7 ConcepTest 11.6a Period of a Spring IA glider with a spring attached to each end oscillates with a certain period. If the mass of the glider is doubled, what will happen to the period?1) period will increase2) period will not change3) period will decrease

8 ConcepTest 11.6a Period of a Spring IA glider with a spring attached to each end oscillates with a certain period. If the mass of the glider is doubled, what will happen to the period?1) period will increase2) period will not change3) period will decreaseThe period is proportional to the square root of the mass. So an increase in mass will lead to an increase in the period of motion.T = 2p (m/k)Follow-up: What happens if the amplitude is doubled?

9 ConcepTest 11.7c Spring on the MoonA mass oscillates on a vertical spring with period T. If the whole setup is taken to the Moon, how does the period change?1) period will increase2) period will not change3) period will decrease

10 ConcepTest 11.7c Spring on the MoonA mass oscillates on a vertical spring with period T. If the whole setup is taken to the Moon, how does the period change?1) period will increase2) period will not change3) period will decreaseThe period of simple harmonic motion only depends on the mass and the spring constant and does not depend on the acceleration due to gravity. By going to the Moon, the value of g has been reduced, but that does not affect the period of the oscillating mass-spring system.Follow-up: Will the period be the same on any planet?

11 ConcepTest 11.8a Period of a Pendulum ITwo pendula have the same length, but different masses attached to the string. How do their periods compare?1) period is greater for the greater mass2) period is the same for both cases3) period is greater for the smaller mass

12 ConcepTest 11.8a Period of a Pendulum ITwo pendula have the same length, but different masses attached to the string. How do their periods compare?1) period is greater for the greater mass2) period is the same for both cases3) period is greater for the smaller massThe period of a pendulum depends on the length and the acceleration due to gravity, but it does not depend on the mass of the bob.T = 2p (L/g)Follow-up: What happens if the amplitude is doubled?

13 ConcepTest 11.10c Pendulum in Elevator IIIA swinging pendulum has period T on Earth. If the same pendulum were moved to the Moon, how does the new period compare to the old period?1) period increases2) period does not change3) period decreases

14 ConcepTest 11.10c Pendulum in Elevator IIIA swinging pendulum has period T on Earth. If the same pendulum were moved to the Moon, how does the new period compare to the old period?1) period increases2) period does not change3) period decreasesThe acceleration due to gravity is smaller on the Moon. The relationship between the period and g is given by:therefore, if g gets smaller, T will increase.gLT=2pFollow-up: What can you do to return the pendulum to its original period?

15 ConcepTest 11.11 Damped PendulumAfter a pendulum starts swinging, its amplitude gradually decreases with time because of friction.What happens to the period of the pendulum during this time?1) period increases2) period does not change3) period decreases

16 ConcepTest 11.11 Damped PendulumAfter a pendulum starts swinging, its amplitude gradually decreases with time because of friction.What happens to the period of the pendulum during this time?1) period increases2) period does not change3) period decreasesThe period of a pendulum does not depend on its amplitude, but only on its length and the acceleration due to gravity.gLT=2pFollow-up: What is happening to the energy of the pendulum?

17 ConcepTest 11.13 Sound It Out1) yes2) no3) it depends on the medium the wave is inDoes a longitudinal wave, such as a sound wave, have an amplitude ?lowhighnormalairpressurexA

18 ConcepTest 11.13 Sound It Out1) yes2) no3) it depends on the medium the wave is inDoes a longitudinal wave, such as a sound wave, have an amplitude ?All wave types — transverse,longitudinal, surface — haveall of these properties:wavelength, frequency,amplitude, velocity, periodlowhighnormalairpressurexA

19 ConcepTest The WaveAt a football game, the “wave” might circulate through the stands and move around the stadium. In this wave motion, people stand up and sit down as the wave passes. What type of wave would this be characterized as?1) polarized wave2) longitudinal wave3) lateral wave4) transverse wave5) soliton wave

20 Follow-up: What type of wave occurs when you toss a pebble in a pond?ConcepTest The WaveAt a football game, the “wave” might circulate through the stands and move around the stadium. In this wave motion, people stand up and sit down as the wave passes. What type of wave would this be characterized as?1) polarized wave2) longitudinal wave3) lateral wave4) transverse wave5) soliton waveThe people are moving up and down, and the wave is traveling around the stadium. Thus, the motion of the wave is perpendicular to the oscillation direction of the people, and so this is a transverse wave.Follow-up: What type of wave occurs when you toss a pebble in a pond?

21 ConcepTest 11.15a Wave Motion I1)2)3)4)5) zeroConsider a wave on a string moving to the right, as shown below.What is the direction of the velocity of a particle at the point labeled A?A

22 ConcepTest 11.15a Wave Motion I1)2)3)4)5) zeroConsider a wave on a string moving to the right, as shown below.What is the direction of the velocity of a particle at the point labeled A?AThe velocity of anoscillating particleis (momentarily) zeroat its maximumdisplacement.Follow-up: What is the acceleration of the particle at point A?

23 ConcepTest 11.16 Out to Sea t t + Dt 1) 1 second2) 2 seconds3) 4 seconds4) 8 seconds5) 16 secondsA boat is moored in a fixed location, and waves make it move up and down. If the spacing between wave crests is 20 m and the speed of the waves is 5 m/s, how long does it take the boat to go from the top of a crest to the bottom of a trough?tt + Dt

24 ConcepTest 11.16 Out to Sea t t + Dt 1) 1 second2) 2 seconds3) 4 seconds4) 8 seconds5) 16 secondsA boat is moored in a fixed location, and waves make it move up and down. If the spacing between wave crests is 20 m and the speed of the waves is 5 m/s, how long does it take the boat to go from the top of a crest to the bottom of a trough?We know that: v = f l = l / T hence T = l / v. If l = 20 m and v = 5 m/s, so T = 4 secs.The time to go from a crest to a trough is only T/2 (half a period), so it takes 2 secs !!tt + Dt

25 ConcepTest 11.18a Wave Speed IA wave pulse can be sent down a rope by jerking sharply on the free end. If the tension of the rope is increased, how will that affect the speed of the wave?1) speed increases2) speed does not change3) speed decreases

26 ConcepTest 11.18a Wave Speed IA wave pulse can be sent down a rope by jerking sharply on the free end. If the tension of the rope is increased, how will that affect the speed of the wave?1) speed increases2) speed does not change3) speed decreasesThe wave speed depends on the square root of the tension, so if the tension increases, then the wave speed will also increase.